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Evaluation of Beckman and Behring nephelometric assays for lipoprotein (a)
37TH ANNUAL CONFERENCE OF THE CANADIAN SOCIETY OF CLINICAL CHEMISTS
D
Haematocrit monitors
effect
on
two
glucose
Boss, S., Dewar, S., Jacklyn, C., Moss, M. and Nickerson, W. Department of Clinical Chemistry, Victoria General Hospital, Halifax, Nova Scotia, B3H 2Y9, Canada We investigated the effect of haematocrit upon whole blood glucose results by the One Touch II (LifeScan Canada Ltd., Burnaby, B.C.)and the Satellite G (MediSense Inc., Cambridge, MA) strip readers. The respective manufacturers claim that the One Touch II produces acceptable glucose results for haematocrits between 25 and 60% and the Satellite G (Sat G) between 35 and 55%. Results from these glucose monitors should be within 15% of the reference method (Diabetes Care 1987; 101:95-9). The study involved adjustment of samples to obtain haematocrit (Hot) readings of 25, 35, 45, 55 and 65% (verified by microhaematocrit analysis). Samples yielding inaccurate haematoerits ( > + 4 % of desired) were omitted; all readings were done in duplicate. Twelve samples were in the normal range; a further eight samples were spiked with
Department of Laboratory Medicine and Lipid Clinic, University Hospital, Vancouver, British Columbia, V5Z 4H4, Canada Lipoprotein(a) [Lp(a)] is a LDL-like complex which contains an additional plasminogen-like protein called apolipoprotein(a) and is recognised as an independent risk factor for atherosclerosis. A reliable automated assay is not currently available for Lp(a) in clinical laoratories. We have compared the performance of two new nephelometric assay methods for Lp(a) [Beckman Array and Behring] to the Pharmacia apo(a) immunoradiometric assay. The Beckman assay, using either fresh or frozen patient specimens, yielded lower values compared to those from the Pharmacia assay and no non-specific reactions were detected. The Behring assay, which currently can use only fresh samples, also gave lower results compared to the Pharmacia method, but recognizable non-specific reactions were detected in approximately 8% of patient specimens. Triglycerides in the form of lntralipid (up to 45 mmol/L) caused no interference with the Beckman assay. The preliminary results are summarised as follows:
glucose.
The following Table shows the observed differences (%) between glucose estimates by the monitors and our reference Beckman Synchron CX 3 (glucose o x i d a s e - O 2 electrode) method. Glucose results were not corrected for the 10% difference between whole blood and plasma. Uaureated Samples
Glucose Added
Ha %
n
One To~.~:~II
Sat G
ra
One Touch 11
Sat G
25
11
5.5
3L0
7
6.1
15.2
35
11
L2
2L1
8
6.8
-0,3
45
10
-6.6
L5
8
L0
-19.5
55
11
-1X1
-22.2
8
-Z1
-4LI
10
-774
-44.4
8
-27.6
-58.6
We concluded that the One Touch II produces acceptable results over the 25-60% haematocrit range and is suitable for use in a tertiary care hospital which manages a large diabetic population. The Satellite G showed rather large errors over the 35-55% haematocrit range and we believe this monitor is not suitable for glucose estimates on anemic or polycythemic patients.
['~
Evaluation of Beckman and Behring nephelometric assays for lipoprotein(a) Urquhart, N. Grierson,R., Bowden,J-F. and Frolich,J.
148
Comparison vs Beckman
Pharmacia ,r Behring
Slope
Intercept
Syx
N
0.801
-32,1
4L9
27
0.802
77.6
90.8
26
There is no available international standard for serum Lp(a), so the accuracy of any one of these methods cannot be directly assessed. Both systems are easier to use than the Pharmcia method, although the Beckman method requires a dilution and centrifugation step before analysis on the Array. Preliminary results indicate that the Beckman and Behring methods may facilitate automated analysis of Lp(a) in the investigation of patients with significant risk for CAD.
Evaluation of a new c r i t i c a l - c a r e m e d i c i n e instrument for real-time electrolytes and blood gas measurements Turcotte, G., L6vesque, M., Nadeau, L. and Jacques, M. Service de Biochimie, H6pital Enfant-J~sus, I401 18 i6me rue, Qu6bec, Quebec, G1J 17_,4, Canada Before implementation at various critical-care sites in our hospital, results from the GEM Premier instrument sold by Mallinckrodt Sensor System were compared with blood gas and electrolyte results from instruments designed
CLINICAL BIOCHEMISTRY, VOLUME 26, APRIL 1993
D
Haematocrit monitors
effect
on
two
glucose
Boss, S., Dewar, S., Jacklyn, C., Moss, M. and Nickerson, W. Department of Clinical Chemistry, Victoria General Hospital, Halifax, Nova Scotia, B3H 2Y9, Canada We investigated the effect of haematocrit upon whole blood glucose results by the One Touch II (LifeScan Canada Ltd., Burnaby, B.C.)and the Satellite G (MediSense Inc., Cambridge, MA) strip readers. The respective manufacturers claim that the One Touch II produces acceptable glucose results for haematocrits between 25 and 60% and the Satellite G (Sat G) between 35 and 55%. Results from these glucose monitors should be within 15% of the reference method (Diabetes Care 1987; 101:95-9). The study involved adjustment of samples to obtain haematocrit (Hot) readings of 25, 35, 45, 55 and 65% (verified by microhaematocrit analysis). Samples yielding inaccurate haematoerits ( > + 4 % of desired) were omitted; all readings were done in duplicate. Twelve samples were in the normal range; a further eight samples were spiked with
Department of Laboratory Medicine and Lipid Clinic, University Hospital, Vancouver, British Columbia, V5Z 4H4, Canada Lipoprotein(a) [Lp(a)] is a LDL-like complex which contains an additional plasminogen-like protein called apolipoprotein(a) and is recognised as an independent risk factor for atherosclerosis. A reliable automated assay is not currently available for Lp(a) in clinical laoratories. We have compared the performance of two new nephelometric assay methods for Lp(a) [Beckman Array and Behring] to the Pharmacia apo(a) immunoradiometric assay. The Beckman assay, using either fresh or frozen patient specimens, yielded lower values compared to those from the Pharmacia assay and no non-specific reactions were detected. The Behring assay, which currently can use only fresh samples, also gave lower results compared to the Pharmacia method, but recognizable non-specific reactions were detected in approximately 8% of patient specimens. Triglycerides in the form of lntralipid (up to 45 mmol/L) caused no interference with the Beckman assay. The preliminary results are summarised as follows:
glucose.
The following Table shows the observed differences (%) between glucose estimates by the monitors and our reference Beckman Synchron CX 3 (glucose o x i d a s e - O 2 electrode) method. Glucose results were not corrected for the 10% difference between whole blood and plasma. Uaureated Samples
Glucose Added
Ha %
n
One To~.~:~II
Sat G
ra
One Touch 11
Sat G
25
11
5.5
3L0
7
6.1
15.2
35
11
L2
2L1
8
6.8
-0,3
45
10
-6.6
L5
8
L0
-19.5
55
11
-1X1
-22.2
8
-Z1
-4LI
10
-774
-44.4
8
-27.6
-58.6
We concluded that the One Touch II produces acceptable results over the 25-60% haematocrit range and is suitable for use in a tertiary care hospital which manages a large diabetic population. The Satellite G showed rather large errors over the 35-55% haematocrit range and we believe this monitor is not suitable for glucose estimates on anemic or polycythemic patients.
['~
Evaluation of Beckman and Behring nephelometric assays for lipoprotein(a) Urquhart, N. Grierson,R., Bowden,J-F. and Frolich,J.
148
Comparison vs Beckman
Pharmacia ,r Behring
Slope
Intercept
Syx
N
0.801
-32,1
4L9
27
0.802
77.6
90.8
26
There is no available international standard for serum Lp(a), so the accuracy of any one of these methods cannot be directly assessed. Both systems are easier to use than the Pharmcia method, although the Beckman method requires a dilution and centrifugation step before analysis on the Array. Preliminary results indicate that the Beckman and Behring methods may facilitate automated analysis of Lp(a) in the investigation of patients with significant risk for CAD.
Evaluation of a new c r i t i c a l - c a r e m e d i c i n e instrument for real-time electrolytes and blood gas measurements Turcotte, G., L6vesque, M., Nadeau, L. and Jacques, M. Service de Biochimie, H6pital Enfant-J~sus, I401 18 i6me rue, Qu6bec, Quebec, G1J 17_,4, Canada Before implementation at various critical-care sites in our hospital, results from the GEM Premier instrument sold by Mallinckrodt Sensor System were compared with blood gas and electrolyte results from instruments designed
CLINICAL BIOCHEMISTRY, VOLUME 26, APRIL 1993